How Air Turns Silver Dark
Silver reacts with trace sulfur-containing gases in the air, especially hydrogen sulfide. At the surface, the reaction forms silver sulfide, a dark compound. The sulfur does not need to arrive as visible dust: even a thin, newly formed film can change how the metal reflects light, making a bright object look gray or black.
Moisture can help these reactions proceed, and the rate depends on the silver’s surroundings. Air near sulfur-containing materials or pollutants may tarnish silver faster. The visible change is therefore a chemical layer growing on the metal, not grime simply collecting on top.
What Polishing Actually Removes
Polishing works by abrading the surface: the cloth or polish wears away the silver sulfide film and exposes brighter metal underneath. That is why a dark mark can come off onto a polishing cloth even though the tarnish was created by a reaction. Polishing is not just washing; it removes a small amount of material, too.
This matters especially for silver-plated objects, whose precious-metal coating is thin. Frequent or aggressive polishing can wear through it. Since tarnish forms at the surface, gentle cleaning can restore the shine—but the same exposed silver can react again when sulfur compounds reach it.
